Planes generally include an adjustable blade and are used in woodworking to flatten and smooth a surface. Conventional planes use blades oriented at an angle (generally between about 12° and 45°) to the sole of the plane and, therefore, to the surface being worked.
When using a shoulder plane and cutting into a corner, it is critical to position the blade with the adjacent edge exactly parallel with or projecting slightly from the body on the working side. Traditional shoulder planes require a manual trial and error process to achieve optimal positioning. In addition, shoulder planes are, by nature, very difficult to hold and to manipulate, since no features can permanently project to either side of the body of the plane since one plane side usually registers against a workpiece during use.
Therefore, it would be beneficial to have a shoulder plane that is more easily handled and that has a blade that is more easily positioned.